Field of the Invention
The present invention relates to a flame-retarding agent, a flame-retardant aqueous resin composition containing the flame-retarding agent, a flame-retardant urethane resin composition containing the flame-retarding agent, and the use therefor. More specifically, the present invention relates to a flame-retarding agent containing a phosphoramidate compound having a specific structure, and a flame-retardant aqueous resin composition that contains this flame-retarding agent and that can be suitably used for a flame-retardant back-coating agent, a flame-retardant coating agent, and other agents. The present invention also relates to a coating agent using this flame-retardant aqueous resin composition and a back-coating agent using this flame-retardant aqueous resin composition, and flame-retardant fiber fabric back-coated with this back-coating agent, as well as a flame-retardant urethane resin composition containing this flame-retarding agent, and a synthetic leather using this flame-retardant urethane resin composition.
Description of Related Art
Hitherto, the back surface of fiber interior materials for vehicles (automobiles, railway vehicles), airplanes, and the like, is subjected to back-coating (backing treatment; backing process), i.e., a back-coating agent (backing agent) is applied to the back surface, to inhibit shedding of the fiber and to increase the strength. To address safety issues, the use of materials to which flame-retardancy is imparted is currently demanded in fields of, in particular, automobiles, etc., and back-coating agents used for these materials are also required to achieve high flame retardancy. Examples of general-purpose flame-retarding agents used in back-coating agents include a halogen-based flame-retarding agent, such as decabromodiphenyl ether combined with antimony oxide.
Although a halogen-based flame-retarding agent generally has excellent properties as a flame-retarding agent, because they contain halogen elements, such as chlorine and bromine, when a product obtained by using a back-coating agent containing such a halogen-based flame-retarding agent is discarded and burnt, hydrogen halide, which is an environmentally hazardous substance, is problematically generated. Further, depending on the type of the halogen-based flame-retarding agent, a substance with greater environmental load, such as halogenated dioxin, is problematically generated. For this reason, avoiding the use thereof or using a reduced amount thereof is desired.
Other than the halogen-based flame-retarding agents, polyphosphate-based flame-retarding agents are effective as a flame-retarding agent. However, polyphosphate-based flame-retarding agents have insufficient water resistance; in particular, they cause problems such as water spots (kiwatsuki) on the surface of fiber products, deteriorating the texture of the products. The term “water spots” as used herein refers to a phenomenon in which high-temperature vapor used in the production of seats for vehicles, as well as moisture, such as rain and sweat, adhere to the surface of a fiber product and allow dissolution of the water-soluble components of the flame-retarding agent, causing the wetted portion to turn into white spots or a stain after drying. To inhibit the formation of water spots, various attempts have been made, such as coating the surface of a polyphosphate-based flame-retarding agent with a silicone compound or a melamine resin (Patent Literature (PTL) 1 and Patent Literature 2). These methods remarkably lessen the formation of water spots caused by ordinary-temperature water; however, the formation of water spots caused by high-temperature vapor or high-temperature water is not sufficiently prevented. To prevent water spots from forming, a compound having low solubility in hot water is in demand, since solubility in hot water is the cause of water spot formation.
In addition to polyphosphate-based flame-retarding agents, there are other flame-retarding agents that contain phosphorus. Among them, phosphoric acid ester-based flame-retarding agents are widely used for, for example, molding resin, urethane foam, and fiber. Some compounds among the phosphoric acid ester-based flame-retarding agents have excellent water resistance. However, many compounds among the phosphoric acid ester-based flame-retarding agents have insufficient flame retardancy when used for back-coating.
Further, synthetic leather has recently been used as a fiber interior material of automobiles, etc., and is also required to have high flame retardancy. As a flame-retarding agent used for synthetic leather, a halogen-based flame-retarding agent, similar to the above back-coating agent, was used; there was, however, an environmental issue since a halogenated gas is generated when the halogen-based flame-retarding agent is burnt, as stated above.
In view of the above, phosphoric acid ester-based flame-retarding agents have been studied (PTL 3 and PTL 4) as effective flame-retarding agents other than halogen-based flame-retarding agents. However, phosphoric acid ester-based flame-retarding agents generally have an unsatisfactory flame-retardant effect, compared with halogen-based flame-retarding agents. To achieve high flame retardancy by using only a phosphoric acid ester-based flame-retarding agent, the use of a special flame-retarding agent and an increase in the amount of the flame-retarding agent are necessary. In either case, the increase in the production cost was problematic.